In certain situations, it is advantageous to control the operation of computer systems using "touchscreen" technologies. For example, touch activated information systems in public places do not require a keyboard or mouse, or other similar hard-to-use and easy-to-damage control devices.
In touch activated computer applications, the system displays images on a screen of a display terminal. The images can include visual option icons or "buttons," with appropriate legends. The user can activate processes corresponding to the visual buttons by pointing at, or "touching" the screen where the buttons are displayed.
Previous touch activated systems have generally sensed the presence of a finger, or pointing device on or near the display screen using capacitance, resistive, acoustic, mechanical, or optical sensors mounted directly on the screen, or around the periphery of the screen, for example, in the bezel of the display terminal.
These sensing techniques generally require a physical modification of the display terminal. For example, in capacitive and resistive systems, transparent layers of conductive and dielectric films are placed directly on the screen. With systems that are acoustically or optically activated, the transmitters and receivers are generally mounted in the bezel or housing surrounding the screen.
The problem with the prior art touch technologies is that the display terminal must be physically modified at an increased cost to receive the sensors. Specialized sensor interfaces and software must also be generated. It is desired to provide a touch activated system without the need to modify the display terminal.